1. Field of the Invention
The present invention relates generally to rechargeable battery systems that include a main battery and at least one auxiliary battery for use in operating vehicles or pieces of machinery, and, more particularly, to a method for detecting a discharge condition fault in an electrical system of a vehicle or piece of machinery receiving electrical energy from a multiple battery system configured to selectively supply electrical energy from the main battery and the auxiliary battery.
2. Description of Related Art
Almost every vehicle utilized today requires a battery to operate. The battery usually initiates an internal combustion reaction that is at the heart of conventional motors. Additionally, with the development of electric and hybrid-electric vehicles that rely directly on batteries to function, there is an increased need for a reliable supply of power from batteries. Recently, significant improvements in battery technologies have allowed conventional-sized batteries to have increased power, increased operating life, better response to discharge and recharge cycling, and lower maintenance requirements than their predecessors. This has allowed for improved starting, as well as prolonged operation of vehicles, equipment, and auxiliary devices.
However, the elements of a conventional battery have changed little, even as many other aspects of vehicle technology and safety have improved. For example, conventional vehicle batteries include a fairly standard sized rectangular casing containing cells (e.g., six cells for twelve-volt batteries and three cells for six-volt batteries). These cells typically contain positive and negative battery plates and electrolytic fluid to allow the battery to store reserve electricity and replenish this reserve from a generating source, such as an electrical system. The battery is typically coupled through a standard set of electrical cables to the electrical system of the vehicle or piece of equipment.
However, a significant problem with existing batteries occurs if, for any reason, the conventional battery loses power or is discharged. The required source for electrical power to start or operate the vehicle or device is lost. Similarly, if, for instance, automobile lights are accidentally left on for extended periods of time without the automobile running, discharge of the battery is inevitable. Additionally, if other auxiliary equipment, such as a radio, fan, or the like, is left on without the engine running, similar problems can occur. A further way the electrical system of a vehicle might fail is through shorts or bad connections to the battery, so that the battery does not recharge during use. This may also occur when a recharging mechanism, such as an alternator or generator, is non-functioning. These are just some of the types of problems or discharge scenarios that may occur in which failure or discharge of the battery leaves the vehicle helpless.
One way to provide power back to the battery in the case of a discharge scenario is through a jump-start. However, this requires an additional vehicle or battery, which may not be available. Jump-starting also subjects both the discharged battery and the jump-starting battery to potential damage, even the possibility of a catastrophic explosion if the electrical connections are improperly coupled. There are also commercially available alternatives to vehicle-to-vehicle jump-starting. These devices primarily comprise portable auxiliary power sources for jump-starting a discharged battery. A major drawback of these devices is that they require the electrical system of the vehicle to be in operable condition to restore the battery. Most of these portable emergency batteries typically comprise a small reserve battery which is plugged into the electrical system of an automobile, for example, through the cigarette lighter plug, and can only be recharged in a household outlet. Because it cannot be recharged from the vehicle, if the discharge recurs for any reason, the user is potentially stranded. These systems, together with the conventional methods of jump-starting a battery, currently provide the only commercially available ways to overcome the loss of power in a battery or other discharge scenario.
Several attempts at improving the functionality of batteries in discharge scenarios by utilizing auxiliary batteries to forestall the need for jump-starting have been attempted, but none have met with any commercial success. These previous commercial attempts at dual battery systems have proven unreliable and cumbersome or worse, non-functional. Many significant drawbacks are seen in many of the early systems, requiring costly modifications due to non-standard battery sizes, modifications to the battery terminals, and/or modification to the electrical system of the vehicle or the device. These modifications made these systems costly to implement and less reliable than the standard sized batteries. Examples of these early attempts include U.S. Pat. No. 3,200,014 to Roberts and U.S. Pat. No. 3,029,301 to Strider.
Another example of these early systems included a three-post system from DELCO. The battery housing had three external terminals extending from the cover: a main battery positive terminal, a reserve battery positive terminal, and a common negative terminal. The negative terminal electrodes of each battery in the system were purportedly connected through a link in the battery housing cover assembly. Thus, this vehicle electrical system required three cables to accommodate the system and required an additional solenoid that was activated during starting. This non-standard configuration meant additional costs and headache for the end-user, requiring special three post batteries and cables. This and the added costs from the need for additional electrical components made the devices commercially unsuccessful.
Additional attempts at achieving a commercially successful system have been made that would fit standard electrical cable configurations, but these have also failed. Vehicle battery systems, like those shown in U.S. Pat. No. 5,002,840 to Klebenow et al. (“the '840 patent”) and U.S. Pat. No. 5,162,164 to Dougherty et al. (“the '164 patent”), show a main and a reserve unit, separated simply by a one-way diode for maintaining the reserve unit in the charged condition during non-use. The main and reserve batteries of the '840 and '164 patents are coupled in parallel with a diode and resistor therebetween and would require only the standard two-post battery configuration. In a normal operating mode, a resistor (for instance, a variable resistance, positive temperature coefficient resistor) precedes the one-way diode. The variable or positive coefficient resistor steps down the amperage to limit the amount of current and, hence, the amount of heat generated by the diode. The diode prevents the reserve battery from discharging to the main battery while allowing current to reach the battery, but it is limited to providing a trickle charge to the reserve battery for recharging. A shunt is provided that is engaged in discharge scenarios to effectively bypass the resistor and diode, and put the two battery units in parallel without the diode, and thereby engage the reserve battery. The entire system is coupled through the negative terminals of each battery that are brought into contact in the parallel circuit.
These circuits and battery configurations have several disadvantages. The diodes described in the '840 and '164 patents are low capacity diodes. These low capacity diodes are problematic in that they have a limited current carrying capacity. Since the low capacity diodes have a relatively small current carrying capacity, they may be destroyed if excessive current is driven through them. For instance, if the full current capacity of a vehicle electrical system were driven through the diode alone, the diode would be destroyed. Thus, these systems need to step down the current with a resistor; however, such stepdown limits the amount of current used to charge the reserve battery. Therefore, these devices and other devices like them are limited to charging the reserve battery with a low current or trickle charge, taking a significant amount of time to recharge the reserve battery. The long duration to charge the reserve battery is a significant disadvantage of such devices in discharge scenarios.
Moreover, the engagement of the shunt in the circuit as described dumps the discharged battery into parallel with the charged battery. The charged reserve battery thus has to contend with both the load placed on it by the vehicle or device and the load of the discharged main battery. Operator error can cause additional problems. If the switch or shunt is inadvertently left in the bypass mode or if an undetected fault occurs in the battery or electrical system, the reserve unit will discharge along with the main unit, thereby impairing the ability of the reserve unit to function as an auxiliary starting battery.
Thus, in a discharge scenario, the devices of the '840 and '164 patents would put added stress on the reserve battery and, potentially, require a long cycle time to recharge the reserve electrical power stored therein. This would be an especially grave problem if the vehicle were to have a short or other electrical system failure, severely limiting the operating time of the vehicle on just the reserve battery.
Similarly, U.S. Pat. No. 5,256,502 to Kump (“the '502 patent”) discloses a set of plates and plate frames, movable bus bars, and circuitry components, including a diode in the circuitry, that allow for recharging of a reserve battery defined from the set of plates and engaged by a switch. The diode prevents current from being drawn from the reserve battery unless a switch is turned to a reserve setting. Similar to the '840 and '164 patents, when the reserve battery plates are selectively engaged, the main and reserve batteries are configured in parallel with each other upon engagement of the switch. Thus, this solution has the same problems as the solutions of the '840 and '164 patents, and similarly couples the negative terminals of the two batteries. The reserve battery is saddled with the load of the electrical system and the load of the discharged main battery when trying to start from a discharge scenario, as engagement draws the reserve electrical energy in the system down. There is no suggestion in any of the aforementioned references of any way to overcome this problem and, in the case of the '502 patent, there is no way to electrically isolate the reserve battery as it is composed of plates shared with the main battery.
In U.S. Pat. No. 6,121,750 to Hwa (“the '750 patent”), a two part battery is disclosed having a microprocessor control switch. The Hwa device contains two twelve-volt batteries in a single housing sharing a common negative terminal end and a single positive terminal. The secondary battery is provided for intermittent engagement to fulfill requirements for short duration, high current output situations. A switch box is provided to permit switching from just the main battery to engaging the main and secondary batteries. Again, the batteries are in parallel when engaged and would be poorly equipped to deal with a discharge scenario for reasons similar to those previously discussed in regards to the other references. Furthermore, there is no indication or suggestion of a diode or similar device provided in the circuitry of the '750 patent for charging the secondary battery and, thus, the secondary battery is not necessarily kept in a charged state because the secondary battery is only providing additional cranking power.
U.S. Pat. No. 5,683,827 to Yu discloses a silicon controlled rectifier for automatically switching off the battery pack when the battery pack generates an output voltage lower than a threshold voltage during a discharge cycle. The rectifier is coupled with individual cells in a series of cells that comprise a battery pack. The system switches packs, but does not provide for reserve electrical energy beyond the individual cells. Moreover, the switching does not teach or suggest an auxiliary battery, nor does it teach isolating an auxiliary battery in case of a discharge scenario.
The performance of all of the heretofore known multiple battery systems have been unsatisfactory. Even with the existing attempts to provide readily available reserve power in a battery, there is still significant room for improvement and a need for emergency starting power. Prior attempts required retrofitting vehicles to accommodate different sized battery housings, different terminal configurations, or remote circuitry, which is often cost prohibitive. To date, no system has been developed to provide the reserve power that is necessary to operate a vehicle or piece of equipment in an emergency and be sufficiently reliable in all situations.
The known multiple battery configurations do not permit disposition of at least two batteries, each capable of delivering sufficient power to start and operate a vehicle, within a housing defined by a conventional vehicle battery envelope and having terminal locations designed to accommodate conventional cable configurations. No system is available that provides the full current of the electrical system of the vehicle to immediately begin recharging an auxiliary battery. In fact, the reliability and safety of previously attempted systems is hampered by diodes with insufficient current-carrying capacity, which may be destroyed during recharge. Additionally, none of the previous devices has been able to provide both a one-way charging circuit and, when needed, the ability to isolate the auxiliary battery to provide emergency power. Finally, none of the prior devices can provide a method for determining whether the cause of the main battery discharge is in the electrical system of the vehicle and still provide the auxiliary power necessary in this situation to get assistance.